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Detection of Antibodies Directed Towards West Nile Virus by PRNT

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Requisition Forms

Reference Details


Serological detection of neutralizing antibodies directed towards West Nile Virus (WNV) by Plaque Reduction Neutralization Test (PRNT).

Test Category:
West Nile virus (WNV)
Illnesses and Diseases:
  • West Nile encephalitis

Serum. Minimum volume of 200 µl required.

Collection Method:

2 mL screw cap tubes.

Specimen Processing, Storage and Shipping:

Store samples refrigerated or frozen until shipped for testing. Ship frozen samples on dry ice, and refrigerated samples on wet ice

Transportation of Dangerous Goods:

Shipping of specimens shall be done by a TDG certified individual in accordance with TDG regulations. For additional information regarding classification of specimens for the purposes of shipping, consult either Part 2 Appendix 3 of the TDG Regulations or section 3.6.2 of the IATA Dangerous Goods Regulations as applicable.


Patient Criteria:

Suspected WNV infection. Submitted samples will first be analysed by the Viral Zoonosis Diagnostic Laboratory by either WNV HAI and/or WNV IgM/IgG ELISA to determine if the patient has developed anti-flavivirus antibodies. Samples that are reactive can be further analysed for the presence of neutralizing antibodies. Samples that are HAI and/or ELISA non reactive (negative) will not be tested by PRNT. This is not a routine test. Please contact the Viral Zoonosis Diagnostic Laboratory before sending specimens.

Accompanying Documentation:

Completed Viral Zoonoses requisition including sender laboratory name, address and telephone number. Patient name and / or identifier (specimen reference number), date of birth, test(s) requested, date of on-set of symptoms, and clinical and travel history of patient.


Initial screening serology such as WNV ELISA must be reactive before samples will be considered for PRNT testing. 

Methods and Interpretation of Results:

The detection of IgG antibodies in a single serum sample is indicative of past or present exposure to this virus. A 4 fold rise or greater in neutralizing antibody titre, or seroconversion in paired sera, is required to document a "confirmed case" of infection.

IgM can persist in serum for up to a year or more after arbovirus exposure.  Thus, detection of IgM by itself is not sufficient for confirmation of acute infection, but is consistent with an exposure at an undetermined time.

Isolation of an arbovirus or detection of nucleic acid by real-time RT-PCR in a clinical specimen provides clear evidence of infection associated with the current clinical illness.


Turnaround Time:

14 calendar days after the completion of ELISA testing.

Phone #: (204) 789-7037
Fax: (204) 789-2018
  1. WHO. 2007. Guidelines for plaque reduction neutralization testing of human antibodies to dengue viruses.